Novel Agents Show Promise as Anti-HIV Compounds

New York (Reuters Health) -- Compounds called pyridine oxide derivatives not only have the ability to inhibit HIV replication in a test tube, they also interfere with viral gene expression [which genes the virus "turns on" or "turns off" -- Ed.], according to the latest research from a team that has been studying these novel compounds.

It may be possible that these new agents could control the ability of HIV to reproduce in both early and later stages of the illness, and may even make the virus enter a dormant state, Dr. Jan Balzarini, Dr. Miguel Stevens, and others from the Rega Institute for Medical Research in Leuven, Belgium suggest.

Previously, Dr. Balzarini found that several pyridine oxide derivatives selectively target HIV-1 reverse transcriptase (RT), acting much like the non-nucleoside reverse transcriptase inhibitors (NNRTIs) [e.g., AZT, 3TC, d4T, among others -- Ed]. "This target is operative before the incorporation of the viral genome in the host cell chromosomes [in other words, before the genetic make-up of the virus inserts itself into the genetic make-up of the cell it infects. -- Ed]," the doctor said.

"But several [other] members of this group of compounds have clearly an inhibitory effect against HIV at a target in the replication cycle of the virus that is operational after the virus is incorporated in the host cell chromosomes," she continued.

These compounds inhibit both HIV-1 and HIV-2 RT and are the focus of the team's latest work, published in the medical journal Antimicrobial Agents and Chemotherapy.

In contrast to the pyridine oxides that inhibit just HIV-1, those that inhibit both HIV-1 and HIV-2 possess a novel dual mode of anti-HIV action independent from HIV RT inhibition, Dr. Balzarini and colleagues report.

"Time-of-addition experiments revealed that these pyridine oxide derivatives interact at a post-integration step in the replication cycle of HIV," they write. "The compounds interfere with the transcription process ... and may have the potential to prevent reactivation of the virus, which is an interesting added value for the compounds," Dr. Balzarini said. [These compounds seem to act at the same place as do other NRTIs as well as at a place farther along in the reproduction of the virus -- Ed.]

"This unique feature, as well as the wealth of chemical modifications that may be introduced into this series of molecules, makes this class of compounds of potential interest as a new lead in the development of candidate drugs for anti-HIV chemotherapy," the researchers write.

Source: Antimicrobial Agents and Chemotherapy, October 2003. Published by www.natap.org.